k: Number of Documents to return. Defaults to 4.
            fetch_k: Number of Documents to fetch to pass to MMR algorithm.
        Returns:
            List of Documents selected by maximal marginal relevance.
        """
        embedding = self.embedding_function(query)
        docs = self.max_marginal_relevance_search_by_vector(embedding, k, fetch_k)
        return docs
[docs]    def merge_from(self, target: FAISS) -> None:
        """Merge another FAISS object with the current one.
        Add the target FAISS to the current one.
        Args:
            target: FAISS object you wish to merge into the current one
        Returns:
            None.
        """
        if not isinstance(self.docstore, AddableMixin):
            raise ValueError("Cannot merge with this type of docstore")
        # Numerical index for target docs are incremental on existing ones
        starting_len = len(self.index_to_docstore_id)
        # Merge two IndexFlatL2
        self.index.merge_from(target.index)
        # Create new id for docs from target FAISS object
        full_info = []
        for i in target.index_to_docstore_id:
            doc = target.docstore.search(target.index_to_docstore_id[i])
            if not isinstance(doc, Document):
                raise ValueError("Document should be returned")
            full_info.append((starting_len + i, str(uuid.uuid4()), doc))
        # Add information to docstore and index_to_docstore_id.
        self.docstore.add({_id: doc for _, _id, doc in full_info})
        index_to_id = {index: _id for index, _id, _ in full_info}
        self.index_to_docstore_id.update(index_to_id)
[docs]    @classmethod
    def from_texts(
        cls,